In the past, specifically, web members, specifically cleaning members such as shown in PTL 1 have generally been sold packaged together after production. In this case, as means for stacking the web members to bunch them together as a preparatory step to packaging, the stacking device such as shown in FIG. 8 may be considered.
FIG. 8 is a schematic side view which shows a conventional stacking device 200. In the stacking device 200 of FIG. 8, web members, specifically the later explained cleaning members 1 are conveyed in a conveyance direction (MD direction) in a state placed on conveyance surface 210s of a conveyor 210, for example, a belt conveyor and are ejected from an end 210e of the conveyor 210 while drawing a parabolic arc. After that, the web members drop down while drawing a parabolic arc, that is, drop down in the vertical direction while moving in the horizontal direction, contact a stop plate 212, and are stacked on a receiving table 214.
At this time, such web members usually include a certain degree of variations in bulk or weight, dimensions, etc. in the individual web members. Therefore, the web members which drop down while drawing a parabolic arc do not always draw the same path while dropping. Further, the web members are formed from fibers etc. and form flat shapes and are light in weight, so are susceptible to air resistance. Therefore, the members are also liable to flip over when dropping. As a result, as shown in FIG. 8, sometimes the web members are not stacked, sometimes are flipped over, and sometimes are conveyed as they are but cannot move on to the packaging step.